1. Field of the Invention
This invention relates to a method for generation of hot gas by incineration of combustible material and an apparatus for generation of hot gas by incineration of combustible material, which method and apparatus are advantageously applicable particularly to the incineration of granular materials such as rice hulls and which produce a combustion gas containing virtually no dust and, therefore, can be used directly as a heating gas.
2. Description of the Prior Art
U.S. Pat. No. 4,159,000 was recently issued relating to an invention entitled "Method for sootless combustion and furnace for said combustion", made by the present inventor and filed with the U.S. Patent Office, with Japanese patent application No. 156474/1976 relied upon for the Convention priority. By use of a cylindrical furnace which is possessed of a funnel-shaped lower section and provided in the ceiling thereof with a stack, the patented invention mentioned above effects the combustion of a given material by blowing the material and air in a tangential direction into the furnace via an inlet disposed in the upper section of the furnace, whereby the incoming mixture of the material and air is made to flow in a fixed spirally descending path along the inner wall of the furnace and burnt at the bottom of the furnace and the combustion gas from the combustion is whirled at the bottom of the furnace and is consequently made to rise in a spirally ascending path in the central portion of the furnace and is discharged through the stack. Although the aforementioned invention is highly effective in preventing pollution of the discharged combustion gas, it still has a possibility that a small portion of dust will be entrained by the combustion gas being released through the stack into the atmosphere. When the thermal energy retained by the discharged combustion gas is utilized as for drying raw cereal, therefore, the gas cannot be used directly and must be used indirectly through the medium of a heat exchanger, for example.